The present invention is generally directed to a control means for use in a hydraulic system of the type which includes a hydraulic cylinder arranged to raise and lower a load, and more particularly, to a control means which releasably locks the hydraulic system in a neutral position to prevent inadvertent actuation of the hydraulic system.
There are many applications where a hydraulic system is utilized for raising and lowering a load or for otherwise controlling movement in relatively opposite directions. One such application is found in a vehicle such as a truck of the type having a dump bed. The vehicle is customarily equipped with a hydraulic pump which is connected to the vehicle transmission which provides fluid under pressure to a hydraulic valve which is in turn connected to a cylinder which raises and lowers the dump bed to facilitate the emptying thereof. For controlling the actuation of the hydraulic system to effectuate the raising and lowering of the dump bed, such systems generally include a control means in the nature of a flexible push-pull or Bowden cable consisting of an outer conduit having therein an inner member which is coupled to suitable valves for controlling the raising and lowering of the dump bed. The inner member is displaceable axially within the outer conduit and upon displacement in a first direction from a neutral position the hydraulic system is actuated for raising the dump bed and upon axial displacement from the neutral position in a second direction the hydraulic system is actuated for lowering the dump bed.
Prior control means for this application have generally included a rigid shaft contained within a tubular member. The tubular member is connected to the outer conduit of a push-pull cable and the inner member of the cable is connected to the rod member. A control knob is fixed on the end of the rod opposite its connection to the cable inner member. When the control knob and thus the rod member is in the neutral position, the hydraulic system is deactuated and maintains the dump bed in a static condition whether fully or partially raised, or completely lowered. Unfortunately, the control means of the prior art have been susceptible to inadvertent displacement of the rod member due to either an accidentally applied force to the control knob or due to vibrations resulting from vehicle movement. As a result, accidental raising or lowering the dump bed of such vehicles has occurred. Such an occurrence not only may necessitate the refilling of the dump bed, but also may create a dangerous condition when a loaded dump bed is accidentally raised during movement of the vehicle, or when the bed may lower with a person under the bed.
It is, therefore, a general object of the present invention to provide a new and improved control means for a hydraulic system.
It is a more particular object of the present invention to provide a control means for a hydraulic system of the type which is arranged to raise and lower the dump bed of a vehicle wherein the control means releasably locks the hydraulic system in a neutral position to preclude inadvertent actuation of the system.
It is a still further object of the present invention to provide a new and improved control means for a hydraulic system of the type which raises and lowers the dump bed of a vehicle which includes a releasable locking device for locking the hydraulic system in a neutral position and which provides ready intentional release of the control means from the neutral position to facilitate intentional actuation of the hydraulic system.